1. Field of the Invention
The present invention relates to environmental engineering, and in particular relates to a system for treating wastewater containing ammonia.
2. Description of the Related Art
Either city or industry wastewater treatment, removing the ammonia is an important factor. The nitrogen exists in the form of ammonium and/or organic nitrogen in the city wastewater and the organic is usually converted to ammonium under an aerobic or anaerobic treatment. In the conversional denitrification process, ammonium is oxidized to become nitrate by bacteria occurs during aerobic condigion, and then the nitrate is reduced to become nigrogen gas and returned to the atmosphere.
In the conversional biological process, ammonium is firstly oxidized by the ammonium oxidation bacteria (AOB) to become nitrite, the nitrite is sequentially oxidized by the nitrite oxidation bacteria (NOB) to become nitrate, and then nitrate is reduced by denitrifying bacteria to become nitrogen gas. Since the high aeration volume and addition of organic materials are required to convert the ammonium to nitrate and provide a carbon source in the conversional treatment, not only excess energy is consumed but also the footprint of aeration unit is large to complete nitrification.
To mitigate the previously mentioned problems, an anammox process is developed. In the anammox process, nitrite which acts as electron acceptor and subsequently combines with ammonium, which also results in the production of nitrogen gas. Before the anaerobic oxidation process, ammoinium shall be converted to nitrite to provide enough electron acceptors. However, because nitrite is a transitional material in the nitrification process, nitrite concentration usually is low and not enough. Thus, the amount of nitrite shall be increased to improve the ammonium oxidation process.